Researchers with African ancestors will find plenty of “wow” factor—and clues to where those family members came from—at this spectacular site from Harvard’s Center for Geographical Analysis. Historical overlays and geographical data trace the slave trade across the Atlantic and the continent.

A 1932 atlas with nearly 700 maps meets 2017 technology at this slick University of Richmond site. Maps have been augmented here in ways impossible in print, animated to show change over time or made clickable to view the underlying data.

Newly being scanned at this federal land records treasure-trove are Control Document Index documents covering public lands, proclamations and withdrawals. These additions will be linked to the existing databases of more than 5 million land titles dating from 1820, plus images of survey plats and field notes.

Pick your viewer—such as Google Maps or Google Earth—to explore the more than 76,000 geographic images in this collection. Overlaying historical maps with modern ones lets you see where your ancestral places are now.

Finally you can search the most important of all German gazetteers, which aimed to list every place name in the German Empire (1871-1918). It gives the location of the civil registry office and parishes if any, along with other information about each place.

The University of Southern Maine is employing the latest imaging technology—a 60-megapixel camera to photograph large maps, a 3-D imager to render globes—to digitize its gigantic cartographic collection. Need a map of postal routes in the Dakota Territory? They’ve got one, and thousands more treasures.